Various gas analyzers have conventionally been known. Examples of such various gas analyzers include a differential pressure gauge that detects gas pressure, a gas densimeter that detects gas density, an infrared spectroscopic analyzer that detects vibrations of gas molecules, and a mass spectrometer that detects the mass number of ionized gas. Further, another various types of devices have been known.
Among gas analyzers, there has been a known device that performs a predetermined analysis after ionizing gas. The gas analyzer of this type may analyze gas which is present in a space or is generated from a sample. The gas analyzer that analyzes gas generated from a sample may have, at a preceding position of an ionizing unit that ionizes gas, a sample chamber for containing the sample and a gas conveyor for conveying gas generated from a sample. A mass spectrometer has been also known as one of the gas analyzers. The mass spectrometer generally includes an ionizing unit that ionizes gas, an ion-separating unit that separates the generated ions for each mass-to-charge ratio, and an ion-detecting unit that detects ion intensity.
Various methods have been conventionally known for providing an ionizing unit in a gas analyzer. For example, there have been known an Electron Ionization (EI) method, a Photo-Ionization (PI) method, and the like. The EI method is an ionization technique in which accelerated electron beams strike gaseous sample molecules to generate ions. The EI method may also be called as an Electron Impact Ionization method. The PI method is an ionization technique in which when sample molecules are irradiated with light, the molecules absorb electromagnetic wave energy thereof to cause ionization of the molecules.
A device disclosed in Patent Document 1 has been conventionally known as a gas analyzer using an ionizing unit. In this device, the EI method and the PI method are selectively performed to carry out mass spectrometry on a sample.
Patent Document 1: Japanese Patent Application Laid-Open Publication No. 2005-093152 (p. 4, FIG. 1)